1. Field of the Invention
The present invention relates to a stocker including a purge function, a stocker unit, and a method for supplying cleaning gas to a container in a stocker.
2. Description of the Related Art
Workpieces handled in a clean room, such as semiconductor wafers and reticles, are transported and stored while being housed in a container such as an SMIF (Standard Mechanical Interface) pod or an FOUP (Front Opened Unified Pod). It has been proposed to keep the interior of the container locally clean by introducing a cleaning gas such as nitrogen (N2 gas) or cleaned and dried air through a gas inlet of the container. Nitrogen gas in particular also serves the role of preventing the formation of an oxide film on the surface of semiconductor wafers. JP 2010-241515A proposes a stocker having a nozzle that supplies cleaning gas to a container, and WO 2008/106622 (JP 2010-520625A) proposes an SMIF pod having a gas inlet for storing reticles.
With the stocker proposed in JP 2010-241515A, all of the cells are compatible with the purge function, and it is not possible for cells compatible with the purge function and cells not compatible with the purge function to coexist. If some of the cells are not provided with a purging tube (purging line), those cells cannot be used for purging. If the purge function is to be added to an existing stocker that does not have purging lines, it is necessary to replace the existing stocker with a new stocker. In the case of altering the stocker in a clean room instead of replacing it with a new stocker, there are limits on the work time and work space, and the raising of dust needs to be prevented, thus making alteration difficult.